Encapsulation of metallic nanowires inside carbon nanotubes for next generation nanostructured device architectures

The focus of this work is to establish novel chemical to generate carbon nanotubes filled with metallic materials, their characterisation, and implementation into optimised device geometries. Properties of metallically filled carbon nanotubes are highly dependent on the synthesis technique implemented and the chemical composition and synthesis environment. The Nanomaterials by Design team have made significant progress with large scale production of carbon nanotubes, facilitating their integration into novel nanoengineered materials for use in a variety of different devices.

Encapsulating the metallic material allows exploitation of the nanoscale properties of the metallic materials protected both mechanically and from oxidation by the carbon nanotube. State-of-the-art chemical vapour deposition synthesis techniques in conjunction with in situ monitoring technologies allow us to engineer the metallic filling and morphology of carbon nanotubes ultimately altering the physical properties of the generated materials. Other synthesis techniques include electrolysis in molten salts of the desired metallic filling and vapour filling of the desired material. Both in situ and ex situ synthesis techniques are implemented for encapsulation of different metallic materials for varying functionality. Such multi-functional nanomaterials can also be produced into flexible composites or utilised individually. For example, thin films of carbon nanotubes filled with a magnetic material are lightweight, strong, and can be perturbed by magnetic manipulation. Materials with these properties are highly sought for robotics, sensing and ultra-high-density magnetic storage devices. Alternatively, metallically filled nanotubes can provide large surface area and structural stability for anode materials in battery applications.

In order to ultimately characterise these materials and confirm their potential application, transmission electron microscopy will be utilised alongside scanning electron microscopy to gauge the degree of filling and morphology of the filled nanotubes. These techniques will be combined with energy-dispersive X-ray spectroscopy and Raman spectroscopy to obtain local compositional data on the fillings. X-ray diffraction will be utilised to characterise the presence of various phases of filled material generated inside the nanotubes to better understanding into the synthesis mechanisms. These results will be correlated to the electrochemical, thermoelectric or magnetic performance of the materials, ultimately providing a feedback loop for the modification of the synthesis procedure, in an iterative fashion, to optimise the desired properties of the materials.

The work will be conducted in collaboration with internationally leading experts in the fields of nanomaterials and electrochemical characterisation respectively. Moreover, the research group has a range of industrial collaborators and specific potential applications will be sought once progress has been made with the metallically filled carbon nanotube materials. Traditionally, the students of the Nanomaterials of Design research group are encouraged to engage with academic collaborators as well as industry partners whenever feasible.

This research project falls within the EPSRC Energy, Engineering, Healthcare technologies, Manufacturing the future, Physical sciences research areas.